Multiple transmitter-antenna switching system



1957 w. s. LEMMON ETAL MULTIPLE TRANSMITTER-ANTENNA SWITCHING SYSTEM 2 Sheets-Sheet 1 Filed Feb. 11, 1955 llllll/Il/ INVENTORS My H E [Z w P H W M W Jan. 15, 1957 Filed Feb. 11, 1953 W. S. LEMMON ETAL MULTIPLE TRANSMITTER-ANTENNA SWITCHING SYSTEM 2 Sheets-Sheet 2 6 Wa/fe/ 5 Lem/non Mark L. Macficiam AOEY IN VENTORS;

United States Patent MULTIPLE TRANSMITTER-ANTENNA SWITCHING SYSTEM Walter S. Lemmon, Riverside, Conn., and Mark L.

MacAdam, Brockton, Mass, assignors to Radio Industries Corporation, New York, N. Y., a corporation of New York Application February 11, 1953, Serial No. 336,338

4 Claims. (Cl. 307-115) This invention pertains to radio apparatus, and more specifically to improvements in selectively connecting and disconnecting one or more radio transmitters with one or more antennas or antenna feed-lines.

The increasing usage of high-power radio transmitters has resulted in complications in the problem of rapidly connecting anyone of a plurality of such transmitters to a radiating antenna system. Occasionally, installations are required in which a single antenna must be rapidly switched between difierent ones of a series of transmitters, or in which there are several transmitters and several antennas, and it is desired to connect a particular transmitter to a particular antenna or its open-wire feeder without loss of time. Various arrangements of mechanical manually operated switches have been proposed, but such arrangements are not adapted to rapid remote control, as from a centralized point, and they involve hazards both to personnel and equipment. in addition, these prior arrangements have usually involved stub lines or dead ends which remain connected to the equipment in use, involving operating difiiculties and mismatch.

The present invention provides a compact and efficient assembly of vacuum switches (that is, switches of a known type in which the circuit is interrupted within an evacuated envelope), the vacuum switch units being connected to peripheral points about a ring-like conductor. This arrangement permits several switches to be connected to a transmitter feeder-line (or an antenna feeder) with a minimum conductor length, thus eliminating the etfect of feeder stubs upon the actual circuits which are in use.

The invention further contemplates simplified and foolproof motorized operating means for each pair of vacuum switches, together with control arrangements by which any pair of switches may be opened and closed rapidly and accurately from a nearby or a remote control station. Such a motorized arrangement makes it extremely simple to provide interlocking and indicating circuits to prevent more than one transmitter being connected to a given antenna, and vice versa.

A further object of the invention is to provide a unit and assembly of the above type in which a known form of vacuum switch is mounted for ready removal and replacement as required, without involving the use of tools or extensive delays in replacement in the event of a switch failure.

The above and other objects and advantages of the invention will best be understood by referring to the following detailed specification of a preferred embodi ment thereof taken in connection with the appended drawings, in which:

Fig. l is a schematic perspective view illustrating the general arrangement of three pairs of vacuum switches with a single transmitter,

Fig. 2 is a fragmentary view, partly in section, showing the arrangement of a ring conductor with three switch units, and with one switch unit shown in side elevation,

Fig. 3 is a fragmentary sectional view taken on line 3-3 of Fig. 2,

Fig. 4 is a plan view of one motorized assembly having one pair of vacuum switches,

Fig. 5 is a view loo-king upward of the bottom of the assembly of Fig. 4, and

Fig. 6 is a schematic wiring diagram of the motor control circuit of such a unit.

In the embodiment of the invention which is described herein, the arrangement is a simple one utilizing three pairs of vacuum switches intended for the selective connection of a single radio transmitter to anyone of three antennas. However, it should be understood that such an assembly may utilizemore or less than three pairs of vacuum switches, and also that several of the assemblies may be connected with one another to increase the switching capacity of the installation. The detailed arrangements of these more complicated installations, together with their control and operating or interlock circuits, will be well within the skill of workers in this art.

Referring now to Fig. 1 of the drawings, numeral 10 designates a radio transmitter whose output at conductors 12 and 14 is to be connected to one or the other of three sets of antenna feed-lines designated 16, 1S and 20. As shown in Fig. .1, this is accomplished by connecting each of the transmitter conductors i2 and 14 to a ring-shaped conductor 22 and 24, respectively. These ring-shaped conductors are formed of flat, ribbon-like material to minimize their inductance and maintain desired impedance. At spaced points on the peripheries of these rings, connections are made to respective vacuum switches such as 2628, 3ii32 and 34-36, each pair of vacuum switches then being connected to the respective leads of one of the antenna feeders 16, 18 and 20.

Each pair of vacuum switches in Fig. l is shown as controlled by an electric motor 38, 40 or 42, so that there is a motorized vacuum switch unit associated with each of the antenna lines. This ring arrangement of the respective motorized vacuum switch units permits the use of extremely short connections from the ring conductors 22 and 24 to the switch elements, the conductor length being much less than that indicated by Fig. l which is expanded in scale for a clear showing of the physical arrangement. Also, due to the construction of the vacuum switches and their mounts, there are only a few inches of conductive material left connected to the circuit when the switches are in their open positions, thus minimizing stub and dead-end etiects.

The actual construction of one complete vacuum switch unit is best illustrated in Fig. 2 of the drawings, which also shows the common connecting link for one output conductor of the transmitter, and the close spacing and compact arrangement made possible by the invention. In Fig. 2, numeral 12 again designates a conductor from a transmitter as in Fig. 1, and numeral 16 designates one conductor of the antenna feeder having the same reference character in Fig. 1. The ring conductor 22 is Shown as connected to conductor 12, the latter passing through an aperture in one wall of a housing 44 which encloses the entire assembly of three motorized switch units. Conductor 16 is shown as passing through another opening in housing 44, and it will be obvious that suitable feedthrough insulators can be employed if desired atthese points.

Three of the vacuum switches corresponding to the three switch units of Fig. 1 are indicated in Fig. 2 by the same numerals (26, 3t} and 34) as in Fig. 1. The three motorized switch units are identical with one another, but as shown, are connected to points on ring 22 spaced about apart, with the transmitter conductor 12 con nected to the 4th peripheral point on ring 22.

By suitable dimensioning of the rings, and the use of flat or ribbon cross-section material in their formation, it is possible to' increase the number of vacuum switch sets connected to one pair of rings up to ten or more, depending upon the highest frequency used in relation to the size or" the ring. Thus, interconnection of multiple high-power (50 kw. or more) transmitters and antennas can be accomplished from a remote point with the introduction of a standing-wave ratio of less than 1.05 per switch, and with positive connection and interlocking of all switches.

The vacuum switch 26 shown in Fig. 2 is a standard commercial item, comprising an evacuated tubular envelope containing a pair of contacts, one fixed in the en velope as at 46, and the other being axially slidable therein as by a flexible bellows 48. Reciprocation of rod 50 extending from the movable contact permits the circuit through the switch to be opened and closed, the resilience of bellows 48 (or of a spring therein) normally forcing the movable contact into circuit-closing position. At

each end of the tubular envelope of switch 26, a circular contact flange 52 is provided, being rigidly connected to the envelope and in electrical connection with the respective contact elements of the switch. In order for the vacuum switch 26 to be readily removable, the present invention provides a pair of spaced spring clips, each of generally U-shaped configuration as best shown in Fig. 2, where numeral 54 designates a relatively rigid U-shaped clip element, while numeral 56 designates resilient fingers of a second U-shaped member normally having its arms placed against the corresponding arms of clip element 54. in this way, the vacuum switch 26 can be slipped into and out of its operative position without the use of tools or the like.

Each of the spaced contact clip assemblies in Fig. 2 is mounted upon the top collar 58 of a vertical stand-ofif insulator 60, the 4 insulators corresponding to each pair of vacuum switches being mounted upon a suitable chassis 62. The contact clip at the right end of vacuum switch 26 is connected as by a lug 64 to the ring 22, and the similar switch contact clips of the other switches 30 and 34 are similarly connected to the ring 22 at the points indicated. Also, the left hand contact assembly of a vertical stand-off insulator 70 whose lower end is secured rotatably on chassis 62 as by a bearing 72. A part of the insulator 70 or of a shaft connected to its lower end extends downward inside the chassis 62, and is connected as by a nut 74 to an operating linkage 76 in turn connected to the shaft of motor 38. Thus, a small rotation of insulator 70 will displace roller 68 (say to the left in Fig. 2) and move flange 66 and rod 50 to the left, thus opening the switch assembly. The lugs 64 and their associated parts, in the arrangement shown, have practically zero effective capacitance, so that these parts (which remain connected to ring 22 when the switches are open) have no effect upon the electrical characteristics of the conductor 12 or the other conductor from the transmitter.

Figs. 4 and illustrate in more detail the layout and relationship of the parts shown in Fig. 2. Thus, the chassis is again indicated by 62, and the vacuum switches themselve by 26 and 28, there being a clip unit 54 at each end of each vacuum switch. The flange on the operating rod of each switch is again denoted by 66, its operating roller being carried at the end of an arm '78 mounted upon the top of rotatable insulators 7t). 72 again designates the bearing carrying the insulator upon the chassis.

Turning now to Fig. 5 of the drawings, which shows the underside of chassis 62, the nut 74 securely connects a rotatable part of each of the insulators in bearing 72 to a crank-arm 80, which is in turn pivotally connected to a link 82, these being pivoted to a crosshead link 84 constrained so that its end connected to links 82 moves in a straight line as by a guide block 86 bolted to the chassis. The upper end of crosshead link 84' is pivoted to a disc 88 driven at a suitable speed from the shaft 99 of motor 38.

The parts are shown in all of the figures with switches 26 and 28 in closed-circuit condition. When motor 38, which is a reversible motor, is energized to turn disc 88 in the direction of the arrow in Fig. 5, link 84 will move upwardly, rotating crank arms in the respective directions indicated thereon. The upper crank arms 78 (Fig. 4) will thus be rotated to open the switch contacts of both vacuum switches 26 and 28. Reversal of motor 38 will cause the disc 88 to rotate counterclockwise (Fig. 5) and the switches will be restored to closed-circuit condition.

In order automatically to interrupt the motor circuit at the points in the rotation of disc 88 corresponding to switch-open and switch-closed condition, a pair of switches 22 and 94 are provided, these being of the normally closed type which are opened when corresponding cam elements 96 and 98 on disc 88 engage the switch operating rollers. One of the switches 92 and 94 is connected in the appropriate motor lead to control the rotation in opposite directions. Thus, as shown in Fig. 6, the operation of a simple toggle switch 100 between its two positions will cause the motor automatically to drive the linkage between its two limited positions. Such a toggle switch can be located near the chassis 62, or equally well at a remote or central point. Where the motor 38 is of a commutator type, a capacitor 102 may be connected across the motor to reduce sparking arising at the commutator. Obviously, the motor control described and illustrated can be subjected to various refinements, for example to provide suitable interlock and safety circuits so that not more than one pair of vacuum switches may be closed at a time.

The invention has been described herein in connection with a preferred embodiment, in accordance with the Patent Statutes, but it is to be understood that the details shown herein are merely exemplary, and that various modifications can be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

l. A vacuum switch operating apparatus, comprising a support, a pair of insulators on said support, a spring contact clip carried by each insulator, a vacuum switch having contact flanges at its ends respectively received in said contact clips, an operating rod extending from one end of said vacuum switch, motor means on said support linked to said operating rod for opening and closing said switch, and a pair of cam switches for interrupting the operation of said motor at predetermined extremes of its travel corresponding to the open and closed condition of said switch.

2. The invention in accordance with claim 1, including another insulator rotatably carried by said support, means on one end of said rotatable insulator connected to said operating rod to move the same, and in which said rotatable insulator linked to said motor for rotation thereby.

3. In a vacuum switch operating mechanism, a chassis, pairs of upstanding insulators on said chassis, a contact clip atop each insulator to receive between pairs thereof individual vacuum switch elements, an insulating post adjacent one insulator of each of said pairs and rotatable on said chassis, means connecting each of said posts with a vacuum switch received in said contact clips to operate said switch upon rotation of said posts, a crank arm at the lower end of each of said posts,

crosshead linkage connecting said crank arms for simultaneous rotation thereof, and motor means connected to said linkage to operate the same.

4. A multiple transmitter-antenna switching system, comprising a pair of similar ring-shaped conductors disposed in parallel spaced-apart relationship on a common axis, a pair of transmitter conductors connected respectively to said ring-shaped conductors at corresponding points on their peripheries, a plurality of pairs of circuit breaking switches of the evacuated envelope type each having a fixed contact and a movable contact, said switches being mounted about said ring-shaped conductors with the fixed contacts of each pair of switches being respectively connected to corresponding points of said ring-shaped conductors by respective connectors having lengths small enough to render negligible, at frequencies as high as 30 megacycles per second, the dead end or stub efiects of any such connectors leading to open switches, the points of connection of said respective switches to said ring-shaped conductors being spaced along the peripheries of the latter from one another and from the connections to said transmitter conductors, and means for operating in synchronism the switches of each pair.

References Cited in the file of this patent UNITED STATES PATENTS 1,557,128 Wilson Oct. 13, 1925 1,658,242 Hunter Feb. 7, 1928 2,082,703 Lanyon June 1, 1937 2,189,549 Hershberger Feb. 6, 1940 2,636,038 Seifried Apr. 21, 1953 

